It is known to provide some manually propellable wheeled vehicles or apparatuses such as bicycles with a motor unit to assist a user in powering the apparatus, especially up sloping terrain, e.g. hills, although the motor unit may sometimes used by itself to power the bicycle over any terrain.
It is also known to utilize an in-wheel motor in an electric motor assisted bicycle such that a transmission can be omitted and the resulting apparatus is easy and simple to manufacture. For such a known electric motor assisted bicycle using an in-wheel motor, it can be manufactured by simply replacing a hub of one wheel with an in-wheel motor, while the pedals drive the rear wheel through a sprocket and a chain in a generally conventional manner. In such an arrangement, no motor drive force need be transferred through the bicycle chain. Therefore, a pedal driving force and a motor driving force are delivered quite separately from each other.
One consequence of the known in-wheel motor arrangement is that it is not feasible for an in-wheel electric motor assisted bicycle to be developed with additional functions such as gear shifting, operating with a clutch, functioning as an exercise bicycle, or using the motor to generate power, i.e. it does not afford easy expansion of its functions. It also creates production and assembly problems as well as replacement parts problems. Where an in-wheel motor fails or requires maintenance, for example, it requires the wheel to be removed thus disabling the bicycle. Under some motor failure or maintenance conditions, it may no longer be possible to rotate the wheel accommodating the in-wheel motor such that it is not even possible to propel the bicycle under manually applied pedal power.
In addition to the known electric bicycle using an in-wheel motor, there is at least one other type of electric bicycle which uses a wheel-driving motor. However, in this type of electric bicycle, a motor driving force and a pedal driving force are also separately delivered from each other. This type of electric bicycle has similar disadvantages in that gear shifting can not be easily realized using a rear wheel transmission when the electric bicycle is being propelled using the wheel-driving motor.
The foregoing are just some of the common problems encountered with conventional hybrid motor assisted pedal driven apparatuses such as bicycles.